removed all the bundled-up return-value structs

they are replaced with tuples and single-purpose bool wrappers

Force-Push: yes
Change-Id: Iabf9c1d3f9dddee160d556004b2a72b15cd6e574

1 files changed, 47 insertions, 76 deletions

diff --git a/src/main.rs b/src/main.rs
index d7791d9..e181e46 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -176,32 +176,12 @@ struct Concurrency {
   image_fences: Vec<vk::Fence>,
 }
 
-// This struct exists for a single use, returning from init_vulkan_instance().
-struct InstanceCreation {
-  instance: Instance,
-  debug_messager: Option<vk::DebugUtilsMessengerEXT>,
-  enable_portability: bool,
-  enable_validation: bool,
-}
-
-// This struct exists for a single use, returning from init_vulkan_device().
-struct DeviceCreation {
-  physical_device: vk::PhysicalDevice,
-  device: Device,
-  indices: QueueFamilyIndices,
-  graphics_queue: vk::Queue,
-  presentation_queue: vk::Queue,
-  enable_swapchain: bool,
-}
+//   These structs exist for use in function calling, to remove the potential
+// for accidentally passing or returning one boolean as if it's another.
+struct EnablePortability(bool);
+struct EnableValidation(bool);
+struct EnableSwapchain(bool);
 
-//   This struct exists for a single use, returning from
-// find_device_swapchain_features().
-#[derive(Debug)]
-struct SwapchainFeatures {
-  capabilities: vk::SurfaceCapabilitiesKHR,
-  formats: Vec<vk::SurfaceFormatKHR>,
-  presentation_modes: Vec<vk::PresentModeKHR>,
-}
 
 impl Surreality {
   fn new() -> Self {
@@ -223,29 +203,27 @@ impl Surreality {
     let window = Self::init_window(event_loop)?;
     let entry = Self::init_vulkan_entry()?;
 
-    let InstanceCreation {
-      instance,
-      debug_messager,
+    let (instance,
+         debug_messager,
 
-      //   There are a few Vulkan features (in the informal sense of
-      // "feature") that we want to be able to run both with and without.
-      // Here, we have booleans describing which we're doing.
-      //
-      //   These are only used to communicate between initialization phases;
-      // we don't keep them around after that.
-      enable_portability,
-      enable_validation
-    } = Self::init_vulkan_instance(&window, &entry)?;
+         //   There are a few Vulkan features (in the informal sense of
+         // "feature") that we want to be able to run both with and without.
+         // Here, we have booleans describing which we're doing.
+         //
+         //   These are only used to communicate between initialization
+         // phases; we don't keep them around after that.
+         enable_portability, enable_validation)
+        = Self::init_vulkan_instance(&window, &entry)?;
 
     let surface = Self::init_surface(&window, &instance)?;
 
-    let DeviceCreation {
-      physical_device, device, indices, graphics_queue, presentation_queue,
-      enable_swapchain
-    } = Self::init_vulkan_device(&instance, &surface,
-                                 enable_validation, enable_portability)?;
+    let (physical_device, device,
+         indices, graphics_queue, presentation_queue,
+         enable_swapchain)
+        = Self::init_vulkan_device(&instance, &surface,
+                                   enable_validation, enable_portability)?;
 
-    if enable_swapchain {
+    if enable_swapchain.0 {
       let swapchain = Self::init_swapchain(
               &window, &instance, &surface, &physical_device, &device,
               &indices)?;
@@ -323,7 +301,8 @@ impl Surreality {
 
   #[allow(unsafe_code)]
   fn init_vulkan_instance(window: &Window, entry: &Entry)
-      -> Result<InstanceCreation>
+      -> Result<(Instance, Option<vk::DebugUtilsMessengerEXT>,
+                 EnablePortability, EnableValidation)>
   {
     let enable_validation = cfg!(feature = "vulkan-validation")
                             || cfg!(debug_assertions);
@@ -375,12 +354,12 @@ impl Surreality {
             vk::KHR_PORTABILITY_ENUMERATION_EXTENSION.name.as_ptr());
         flags.insert(vk::InstanceCreateFlags::ENUMERATE_PORTABILITY_KHR);
 
-        true
+        EnablePortability(true)
       } else {
-        false
+        EnablePortability(false)
       }
     } else {
-      false
+      EnablePortability(false)
     };
 
     // Request the LunarG validation layer, when appropriate.
@@ -390,15 +369,15 @@ impl Surreality {
       if available_layers.contains(&validation_layer_name) {
         layers.push(validation_layer_name.as_ptr());
 
-        true
+        EnableValidation(true)
       } else {
         eprintln!("Vulkan validation requested at build time, \
                    but no validation layer available.");
 
-        false
+        EnableValidation(false)
       }
     } else {
-      false
+      EnableValidation(false)
     };
 
     //   Request the debug extension. This is the first of three bits of code
@@ -471,12 +450,7 @@ impl Surreality {
       None
     };
 
-    Ok(InstanceCreation {
-      instance,
-      debug_messager,
-      enable_portability,
-      enable_validation,
-    })
+    Ok((instance, debug_messager, enable_portability, enable_validation))
   }
 
   // TODO this is so short that it can likely be eliminated
@@ -501,8 +475,10 @@ impl Surreality {
 
   #[allow(unsafe_code)]
   fn init_vulkan_device(instance: &Instance, surface: &vk::SurfaceKHR,
-                        enable_validation: bool, enable_portability: bool)
-      -> Result<DeviceCreation>
+                        enable_validation: EnableValidation,
+                        enable_portability: EnablePortability)
+      -> Result<(vk::PhysicalDevice, Device, QueueFamilyIndices, vk::Queue,
+                 vk::Queue, EnableSwapchain)>
   {
     let physical_device = Self::pick_vulkan_device(instance, surface)?;
 
@@ -533,7 +509,7 @@ impl Surreality {
 
     let validation_layer_name = vk::ExtensionName::from_bytes(
                                     b"VK_LAYER_KHRONOS_validation");
-    if enable_validation {
+    if enable_validation.0 {
       //   It's not concerning if this isn't supported, because device
       // layers are ignored on recent versions, they're purely historical.
       if available_extensions.contains(&validation_layer_name) {
@@ -543,7 +519,7 @@ impl Surreality {
 
     let portability_extension_name = vk::ExtensionName::from_bytes(
                                          b"VK_KHR_portability_subset");
-    if enable_portability {
+    if enable_portability.0 {
       //   This is untested, since the only scenario where it would come up
       // is on a Mac, which we don't actually support. Sorry, and good luck.
       if available_extensions.contains(&portability_extension_name) {
@@ -567,12 +543,12 @@ impl Surreality {
       {
         extensions.push(swapchain_extension_name.as_ptr());
 
-        true
+        EnableSwapchain(true)
       } else {
-        false
+        EnableSwapchain(false)
       }
     } else {
-      false
+      EnableSwapchain(false)
     };
 
     //   We have one or more queue family indices; we don't know a priori
@@ -617,14 +593,9 @@ impl Surreality {
       device.get_device_queue(indices.presentation, 0)
     };
 
-    Ok(DeviceCreation {
-      physical_device,
-      device,
-      indices,
-      graphics_queue,
-      presentation_queue,
-      enable_swapchain
-    })
+    Ok((physical_device, device,
+        indices, graphics_queue, presentation_queue,
+        enable_swapchain))
   }
 
   #[allow(unsafe_code)]
@@ -634,7 +605,7 @@ impl Surreality {
                     indices: &QueueFamilyIndices)
       -> Result<Swapchain>
   {
-    let SwapchainFeatures { capabilities, formats, presentation_modes }
+    let (capabilities, formats, presentation_modes)
             = Self::find_device_swapchain_features(
                   instance, surface, physical_device)?.require()?;
 
@@ -1226,7 +1197,9 @@ impl Surreality {
   fn find_device_swapchain_features(instance: &Instance,
                                     surface: &vk::SurfaceKHR,
                                     physical_device: &vk::PhysicalDevice)
-      -> Result<Acceptable<SwapchainFeatures>>
+      -> Result<Acceptable<(vk::SurfaceCapabilitiesKHR,
+                            Vec<vk::SurfaceFormatKHR>,
+                            Vec<vk::PresentModeKHR>)>>
   {
     let capabilities = unsafe {
       instance.get_physical_device_surface_capabilities_khr(
@@ -1246,9 +1219,7 @@ impl Surreality {
     } else if presentation_modes.is_empty() {
       Ok(Acceptable::Rejected("No matching presentation modes.".to_string()))
     } else {
-      Ok(Acceptable::Accepted(SwapchainFeatures {
-        capabilities, formats, presentation_modes
-      }))
+      Ok(Acceptable::Accepted((capabilities, formats, presentation_modes)))
     }
   }